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 R/V Roger Revelle location during CLIVAR cruise I5, Week 03 in the Indian Ocean. CLIVAR I5 Weekly Science Report 0305 April 2009R/V Roger Revelle from Jim Swift, SIO, Chief Scientist and Greg Johnson, NOAA/PMEL, Co-Chief Scientist 33.9°S, 51.6°E; 1630 Z (1930 local); 20.1°C (68°F); Winds 6 knots from SSE We are now working our way east across the Madagascar Basin, currently taking a CTD station every 55 km, and have just completed our 54th station. All science systems are working very well, and the weather remains good, though air temperatures have cooled a few degrees, as expected. We continue to experience swell from the south, amplitude modulated on the synoptic time-scales, generated by the big Southern Ocean storms that circle Antarctica. Our primary task is to carry out nearly 200 CTD/rosette stations, each done to the best of our a_ilities, meanwhile maintaining a consistency of calibration and documentation that will not only enable rigorous comparisons of data across our transect, but also make possible accurate determination of individually-small ocean water property changes on comparison with data from other years. Every indication is that our mission is going well indeed, though we are all aware we have many weeks to go before we reach Australia. Taking as much data as we are, it would be peculiar indeed if we did not find interesting and unexpected oceanographic features now and again. For example, Francois Ascani, who is working with PI Eric Firing on the ADCP and LADCP data, found a distinctive high vertical mode signal on the peak of the Madagascar Ridge on a station taken 10-20 km from Walter's Shoal. The signal is clearly captured by both the ship's hull-mounted Hydrographic Doppler Sonar System (an ADCP system unique to the Revelle thanks to SIO PI Robert Pinkel) and the lowered Acoustic Doppler Current Profiler on the Rosette.  HDSS profile of vertical velocity (Francois Ascani) Mishaps do occur. During the recovery of one cast last week, just as the CTD was being raised out of the water, a retaining spring on the winch failed, resulting in loss of control. The winch operator alertly hit the emergency stop, at which point the wire started free-wheeling, with the package falling toward the ocean floor. However, the operator quickly engaged the emergency brake, stopping the package after only 18 meters of descent. His quick and professional actions impressively averted disaster. The chief engineer and his team were able to diagnose and fix the unusual equipment failure in less than two hours, competently minimizing loss of time to the program. Finally, there are two members of the crew who we don't mind telling us that "we try to make things as difficult as we can for you". These valued and hard-working individuals are Jay and Mark, our two cooks. They indeed continue to keep us very well fed and happy. All is well. |
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